1. Field of the Invention
The present invention relates to a reconfigure lock for a dual detector in a gamma camera, for use in nuclear medicine.
2. Description of the Background Art
Gamma ray cameras are relatively well known devices used to detect gamma ray emissions from radioactive decay. A known gamma ray camera described in U.S. Pat. No. 3,011,057 for RADIATION IMAGE DEVICE, hereby incorporated by reference, uses a single sodium iodide (xe2x80x9cNaIxe2x80x9d) scintillation detector crystal to detect gamma ray emissions. The detector crystal is positioned to receive a portion of the gamma ray emissions from the radioactive decay. When a gamma ray strikes and is absorbed in the detector crystal, the energy of the gamma ray is converted into a large number of scintillation photons that emanate from the point of the gamma ray""s absorption in the detector. A photomultiplier tube, optically coupled to the detector crystal, detects a fraction of these scintillation photons and produces an electronic signal that is proportional to the number of detected incident scintillation photons. The gamma ray camera typically has several photomultiplier tubes placed in different positions, with the signals from the different photomultiplier tubes being combined to provide an indication of the positions and energies of detected gamma rays.
Gamma ray cameras are frequently used in nuclear medical imaging to record pictures of a radiation field emanating from a subject""s body. The gamma rays originate from a decay of a radioactive tracer that has been introduced into the subject""s body. The radioactive tracer, such as 99mTc, is a pharmaceutical compound to which a gamma ray emitting nuclide has been attached and which undergoes some physiological process of interest after introduction into the body. For example, the tracer may accumulate in certain organs or tissues of interest, and thus provide an image of those organs or tissue.
Gamma ray cameras use detectors with a wide field of view to image the full width of the patient at each angular stop. Originally, gamma ray cameras used only one detector. This one detector was positioned above an organ that was to be imaged. This one detector was used for single photon emission computerized tomography (SPECT) or emission computerized tomography (ECT). SPECT and ECT require rotating the detector about the patient to obtain tomographic data and images. Technology then developed so that the gamma camera was passed over the entire body of the patient to obtain a complete image (whole body imaging).
Recent technological innovations in gamma ray cameras have produced dual detector systems in order to increase efficiency. These dual detector systems have their detector image director arrows oriented at a fixed angle of 180xc2x0. Having dual detector systems with the ability to have a fixed angle of 180xc2x0 is very important so that the detectors can rotate about the patient only 180xc2x0 rather than a full 360xc2x0 rotation. For a total body scan, the detector is required to move along the entire length of the patient""s body. The dual head system is more efficient because image data for both the anterior and posterior images can be obtained simultaneously. This can reduce the scan time up to one half. Reducing scan time reduces the cost of diagnosing the patient as well as reducing the time of patient discomfort. In addition, the system can be optimally configured by providing angular displacement between two detectors adjusted to any angle between 90xc2x0 and 180xc2x0. Triple head systems have also been developed that have their image direction arrows oriented at fixed angles of 120xc2x0. Depending on the application, each of these cameras, (single, dual and triple), have certain features that are advantageous over another. Factors used to determine which system to use include the ability of the camera to perform the tasks, the quality of the images desired.
It is a goal of the present invention to present an improved method of a reconfigure lock for a dual detector gamma camera.
The present invention provides a reconfigure lock for a dual detector gamma camera with triple race bearing (outer, center and inner). The outer race serves as the supporting frame, the center race and inner races have the detectors mounted onto them. A lock assembly is mounted onto the inner race. The center and inner races rotate in unison when locked to one another. The center race has a separate locking segment for each individual configuration angle. The outward movement of the lock slide disengages it from the lock segment and engages it in the outer race pocket (locking pocket). When reconfiguration is complete, two switches (one in the lock and one in one of the segments) are closed.